Drug Interactions between milnacipran and Ormazine

GENERALLY AVOID: Use of milnacipran in conjunction with chronic alcohol consumption may potentiate the risk of liver injury. Milnacipran alone can increase serum transaminase levels. In placebo-controlled fibromyalgia trials, increases in ALT were more frequently observed in patients treated with milnacipran 100 mg/day (6%) and 200 mg/day (7%) compared to patients treated with placebo (3%). One patient receiving milnacipran 100 mg/day (0.2%) had an increase in ALT greater than 5 times the upper limit of normal (ULN) but did not exceed 10 times the ULN. Increases in AST were also more frequently observed in patients treated with milnacipran 100 mg/day (3%) and 200 mg/day (5%) than in patients treated with placebo (2%). There have been reported cases of increased liver enzymes and severe liver injury, including fulminant hepatitis, from foreign postmarketing experience with milnacipran. Significant underlying clinical conditions and/or use of multiple concomitant medications were present in the cases of severe liver injury.

MANAGEMENT: Due to the risk of liver injury, patients prescribed milnacipran should be counseled to avoid excessive use of alcohol. Milnacipran should generally not be prescribed to patients with substantial alcohol use.

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.

MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.